Add shared report value conversion

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Shared reporting and PromptKit v0.20.0 implementation plan
 
-Status: ready for implementation; no stages completed.
+Status: implementation in progress; Stage 1 complete.
 
 ## Scope, authority, and execution
 
@@ -61,6 +61,10 @@ writer, or upstream-domain correctness guarantee is added by this plan.
 
 ## Stage 1: Shared report representation and safe YAML conversion
 
+**Complete.** JSON normalization and safe YAML conversion are implemented.
+Focused conversion tests and the root workspace suite (`GOTOOLCHAIN=local go
+test ./...` with Go 1.27.0) passed.
+
 Start in the root package beside [reporter.go](../../reporter.go). Add private
 report normalization using `encoding/json`: marshal the original report value,
 then decode with `UseNumber` into maps, sequences, scalars, null, and